regexp-ast.js

// RegExp:

/x*?/

// 1. Char is main, repetition is secondary (modifier)

{
  type: 'Char',
  value: 'x',
  modifier: {
    value: '*',
    nonGreedy: true
  }
}

// 2. Repetition is main, char is secondary (expression)

{
  type: 'Repetition',
  modifier: '*',
  nonGreedy: true,
  expression: {
    type: 'Char',
    value: 'x'
  }
}